As we age, our memory declines. What if I told you that a “simple” and “easy” winning strategy for improving your memory was the result of research by real scientists at a university that has produced five Nobel Prize winners, including one former associate dean for undergraduate education? With credentials like that, maybe you’ll believe me.
The study was published last July, and the university’s press office ran a ridiculous story claiming that participants’ memory had “dramatically improved” after the intervention. Is this a miracle drug or a memory-boosting game for your smartphone? No. It’s about wafting essential oils for two hours every night.
Reading the exaggerated press releases reminds me of carnival barkers whose job it is to sell tickets by exaggerating the truth. A double-armed man is dubbed the Seal Man, and a desiccated ray carcass is proclaimed a basilisk, a creature that will kill you on sight. Why would they make such a big deal out of such a boring reality?
The connection between smell and neurological disorders is very real and intriguing. But what about this latest study on essential oils? It’s not worthy of a carnival barker’s fanfare.
I smell a warning
Smells can be powerful triggers for distant memories, sometimes referred to as the Proustian phenomenon. In one of his books, French novelist Marcel Proust wrote: Swan’s Way How to eat it Madeleine The cake, soaked in lime blossom tea, flooded the narrator’s mind with childhood memories. (Interestingly, during the writing of the novel’s manuscript, the details were changed from toasted bread laced with honey to the now legendary and very French bread.) Madeleine and tea mix.
There’s also a strange and persistent connection between smell and brain problems that often goes unnoticed. Loss of smell can be an early warning sign of various neurological diseases, such as Alzheimer’s and Parkinson’s. The change may feel like it’s affecting your sense of taste, not your sense of smell. This is because the unique taste of what we eat and drink is often determined by volatile molecules that float up from the back of our throats to our noses as we swallow. Our sense of taste is actually limited to detecting sweet, sour, bitter, salty, savory, and the chalky texture or metallic stinging qualities of blood.
However, not everyone who loses a partial sense of smell will develop dementia or other neurological disorders. More than half of people between the ages of 65 and 80 experience a change in their sense of smell, and the rate rises to three-quarters in people over 80. Unfortunately, this is a common consequence of aging. Besides aging and neurological disorders, there are other causes, such as respiratory infections, such as COVID-19.
However, this loss of smell as an early warning sign of brain damage cannot be ignored. In Alzheimer’s disease, this smell loss is progressive and often occurs early, occurring in more than 90% of patients. In Parkinson’s disease, smell loss is common and relatively stable, regardless of the stage of the disease, and is also present in more than 90% of patients, often appearing years before the disease begins to affect movement. This specific symptom is also associated with other diseases such as Down’s syndrome and Lewy body disease.
And while multiple studies have shown it’s associated with increased mortality, it’s not entirely clear what’s going on here. As we age, we tend to lose all function of our noses. and It makes sense that there would be a link between our sense of smell and our sense of smell as we approach death. But one study showed that a decline in smell was specifically linked to increased mortality from neurodegenerative and cardiovascular diseases. As always, more research is needed.
Given the link between loss or change in smell and disease and death, one might wonder if there are ways to preserve our sense of smell as we age. That’s where this latest research into aromatherapy comes in: There’s evidence that an enhanced sense of smell — being surrounded by a variety of smells — improves brain activity in both lab animals and humans.
The idea is that smelling different essential oils as you fall asleep could act as a kind of brain tonic, warding off memory loss.
However, this study actually show?
Results that don’t pass the smell test
Researchers at the University of California, Irvine distributed aroma diffusers to older adults who had not been diagnosed with cognitive impairment. Each night, these adults attached a specific vial to the diffuser, containing one of seven essential oils (undiluted): rose, orange, eucalyptus, lemon, peppermint, rosemary, and lavender. At bedtime, the diffuser released one aroma into the air for two hours and then stopped. The idea was to enrich their lives with seven different scents to keep their brains active, and each night a different scent would be perceived by the brain as “new” and keep the brain active. Participants randomly assigned to the control group were given a vial that contained mostly water and almost no essential oils. The entire study lasted for six months.
According to a press release, participants who sniffed the undiluted essential oils “saw a 226% improvement in cognitive performance compared to the control group.”
In fact, participants were given four tests before the start of the experiment and at the end. Participants were given a string of numbers that they had to repeat in the same order (e.g. 4-2-9-1). Participants were given a string of numbers that they had to repeat in reverse order (e.g. 3-8-4-2 becomes 2-4-8-3). Participants were given a string of letters and numbers that they had to repeat with the letters in alphabetical order and the numbers in ascending order (e.g. 21-B-11-X becomes BX-11-21). To be clear, there were no differences between the essential oil group and the control group in any of these tests.
In the fourth test, the researchers read a list of 15 words to each participant, who was then asked to repeat it in any order. The same list was read a second, third, fourth, and fifth time, and participants had to remember the words each time and recall as many of them as possible. On the fifth trial, only In the fifth trial, participants in the essential oil group performed better than those in the control group.
You may be wondering, how many people were in each group? Initial enrollment for the study initially recruited 43 people, though they had a goal of recruiting 200. Then the COVID-19 pandemic put the study on hold, forcing scientists to follow participants virtually. Compliance was variable. Finally, when it came time to calculate which group performed better on these cognitive tests, data from only 23 participants was used: 12 in the essential oil group and 11 in the control group.
It’s almost inappropriate to describe these lackluster results (memory improved in 6 of 12 people who took essential oils vs. 3 of 11 controls on the fifth try in just one of four cognitive tests) as a “memory spike,” as the press release puts it, and to turn the smell-memory connection into “a simple, noninvasive technique that may enhance memory and prevent dementia.” The results are very much in line with what you’d find by mere chance; if you test a small enough group of people on enough variables, you should be able to roll the dice and find an association.
Other attempts to show aromatherapy benefits for memory have also been of limited quality. A 2014 review of the use of sage revealed significant flaws in sample size, study design, and transparency. A 2020 review of rosemary incorrectly described studies done on animals (the totality of the evidence considered) as “clinical studies,” a term that refers only to experimental data in humans. For lavender, a 2022 review identified two studies that were not properly blinded, did not recruit many participants, and reached opposite conclusions.
Rachel Hertz, a PhD in psychology and expert on the psychology of smell, wrote in a review article on the role of smell-evoked memories in health that the therapeutic potential of smell “is not a proof point for aromatherapy,” which has had little success “due to a lack of scientific rigor and confusion about mechanisms.” Sure, having vanilla or lavender scents wafting through your home may be pleasant and improve your mood temporarily, but it’s unlikely to ward off dementia.
But the problem with hype is that consumers quickly lose their hard-earned money. The University of California, Irvine study has a commercial side: it was funded by Procter & Gamble, the American multinational corporation whose brands include Febreze, Olay, Ivory, Old Spice and Herbal Essences. Two of the study authors say they received travel expenses and fees for on-site presentations from the multinational corporation, and the paper thanks four Procter & Gamble employees by name for “support and helpful discussions.”
The press release continues the story: “Based on their research, products designed for people to use at home are expected to hit the market this fall.” In their paper, the scientists point out that diffusers have limitations. only One scent released every night. Perhaps Procter & Gamble has come up with a solution.
So that’s where we’re at. This fall, we can almost hear the loud and clear voice of a carnival barker vying for our attention: “Maintain healthy brain function in old age with this simple trick! A cutting-edge machine backed by real science will tickle your brain in the middle of the night with seven scents! Rosemary! Peppermint! Lavender! Enhance memory! Restore your senses! Support your brain! Here you go!”
Take home message:
– A loss or change in your sense of smell can be an early symptom of neurological diseases such as Alzheimer’s or Parkinson’s disease, but it is also common in older age and can be caused by other factors such as respiratory infections.
– A University of California, Irvine study found that exhaling in the scent of essential oils at night dramatically improved memory, but the study was small and only showed improvement on the fifth try of one of four cognitive tests.
– The study was funded by the multinational corporation Procter & Gamble, which plans to launch an essential oil diffuser this autumn based on the mediocre findings.
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